Metal studs are used to form walls in building structures today, including load bearing walls such as exterior walls and curtain walls. In a typical installation, the metal studs are secured by screws at their lower ends to a bottom track secured to a floor, and extend at their upper ends into a top track secured to overhead joists which may form the framework for an upper floor. The upper ends of the studs generally also are secured to the top track. Exterior wall materials and/or wall boards or other panels are applied to the sides of the studs to form a closed wall structure.
The load bearing walls are subject to axial loads (compressive loads on the studs) applied to the studs through the overhead joists, and also may be subject to transverse loads (for example, exterior walls may be subject to transverse loads from wind effects) and lateral loads acting in the plane of the wall. These loads may cause flexing (including bowing, twisting or other deformation of the stud) or turning of the metal studs which may cause the walls to crack or otherwise be flawed or damaged. In load bearing walls, this problem is structural as well as aesthetic.
Bridging systems heretofore have been used to reinforce the metal stud walls by adding structural support between adjacent studs. Three known bridging systems include braced channel, welded channel, and block-and-strap bridging systems.
In the braced channel bridging system, a U-shape channel spans two or more metal studs, extending through a conduit hole in the web of each stud. An angled brace is fastened to both the channel and the web of the stud, generally with screws or rivets.
The welded channel bridging system also uses a U-shape channel which spans two or more metal studs and extends through conduit holes in the webs of the studs. The channel is then welded to the studs on one or both sides of the channel.
In the block-and-strap bridging system, sheet metal “blocks” are fastened between adjacent studs through bent tabs at their distal ends. Then a strap is fastened to one or both sides of two or more metal studs as well as to the respective side or sides of the blocks. Thus the studs are interconnected by the blocks between the studs as well as the straps along the sides of the studs, and the blocks and straps also are connected to each other.
The installation of metal stud wall systems, including the-reinforcing bridging systems, heretofore has been a time consuming process. In a typical installation where the metal studs are fastened at their upper ends to a top track or channel, the attachment positions of the studs are marked off along the top track. Then each stud is fastened to each flange of the top track by screws. A ladder or a scaffold may be, required if the top track is too high for the installer to reach. If a ladder is used, the installer climbs the ladder and fastens as many studs as he can reach to the near flange of the top track. Then he must climb down the ladder, move the ladder along the wall so that when he again climbs the ladder he can reach the next one or more studs for fastening to the top track. If a scaffold is used, much more time is expended setting up the scaffold. After doing this along one side of the wall, the process is repeated on the other side of the wall to fasten the studs to the other flange of the top track.
The metal studs must then be fastened at their lower ends to a bottom track or channel. Each stud must be carefully aligned and squared before being fastened to the bottom track. In addition, the bridging members described above also must be installed to interconnect the metal studs at one or more points between the top and bottom tracks. Because of the time consuming nature of the installation process, fasteners can be missed or forgotten. In the welded channel bridging systems, welders and their equipment are relatively expensive, and welds also can be missed, or can be improperly formed. Defects in welds can be particularly difficult to detect.
In addition, once the studs are installed, other trades people, such as plumbers and electricians, may remove the bridging members between two studs to give them more room to work, running plumbing lines or electrical lines, for example. If the bridging member is not replaced, the strength of the wall may be reduced.